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101.
102.
Hydration of rhyolitic glass during weathering as characterized by IR microspectroscopy 总被引:1,自引:0,他引:1
Tadashi Yokoyama Satoshi Okumura Satoru Nakashima 《Geochimica et cosmochimica acta》2008,72(1):117-125
The mechanism and rate of hydration of rhyolitic glass during weathering were studied. Doubly polished thin sections of two rhyolites with different duration of weathering (Ohsawa lava: 26,000 yr, Awanomikoto lava: 52,000 yr) were prepared. Optical microscope observation showed that altered layers had developed along the glass surfaces. IR spectral line profile analysis was conducted on the glass sections from the surface to the interior for a length of 250 μm and the contents of molecular H2O (H2Om), OH species (OH) and total water (H2Ot) were determined. The diffusion profile of H2Om in Ohsawa lava extends beyond the layer observed by optical microscope. The content of H2Om in the hydrated region is much higher than that of OH species. Thus, the reaction from H2Om to OH appears to be little and H2Om is the dominant water species moving into the glass during weathering. Based on the concentration profiles, the diffusion coefficients of H2Om(DH2Om) and H2Ot(DH2Ot) were determined to be 2.8 × 10−10 and 3.4 × 10−10 μm2 s−1 for Ohsawa lava, and 5.2 × 10−11 and 4.1 × 10−11 μm2 s−1 for Awanomikoto lava, respectively. The obtained DH2Om during weathering are more than 2-3 orders of magnitude larger than the diffusion coefficient at ∼20 °C that is extrapolated from the diffusivity data for >400 °C. This might suggest that the mechanism of water transport is different at weathering conditions and >400 °C. 相似文献
103.
Ken Furuya Osamu Hasegawa Takashi Yoshikawa Satoru Taguchi 《Journal of Oceanography》1998,54(5):545-552
The light-saturated maximum value (P
B
max) and initial slope (α) of the photosynthesis-irradiance (P-E) curve were examined in a warm streamer, a cold streamer and
a warm core ring off the Sanriku area in the subarctic western North Pacific Ocean during an ADEOS/OCTS Sanriku field campaign
in early May 1997. BothP
B
max and α were within the ranges of temperate populations. A regional difference was apparent inP
B
max: populations in the warm streamer tended to show higher value ranging between 1.92 and 4.74 mgC (mgChla)−1h−1 than those in the cold streamer and the warm core ring (1.35–2.87 mgC (mgChla)−1h−1). A depth variation was also observed in α in both the warm streamer and the warm core ring: shallow populations tended to
have lower α than deep populations. The depth variations in bothP
B
max and α resulted in a lower light intensity of the light saturation in a deeper population than that of a shallower one. These
depth-related variations in the P-E parameters were likely a manifestation of “shade-adaptation” of photosynthesis. Photoinhibition
was not observed over in situ surface light intensity varying below ca 1600 μmol photon m−2s−1. Water-column primary productivity was biooptically estimated to be 233 to 949 mgC m−2d−1 using vertical distributions of the P-E parameters, chlorophylla, phytoplankton light absorption and underwater irradiance. Applicability of surface data sets for estimation of water-column
productivity is discussed. 相似文献
104.
Song JY Nakayama K Murakami Y Jung SJ Oh MJ Matsuoka S Kawakami H Kitamura S 《Marine pollution bulletin》2008,57(6-12):889-894
As basic research for the effect of heavy oil on the fish immune system, in this study, the number of leukocyte was counted in Japanese flounder Paralichthys olivaceus, after exposure to heavy oil at a concentration of 30 g/8L for 3 days. To compare the numbers of bacteria in the skin mucus between oil-exposed and control fish, viable bacteria were enumerated by counting colony forming unit (CFU). Compared with 5.79+/-1.88 x 10(7)leukocytes/mL in the controls, the exposed fish demonstrated higher counts, averaging 1.45+/-0.45 x 10(8)cells/mL. The bacterial numbers of control fish were 4.27+/-3.68 x 10(4)CFU/g, whereas they were 4.58+/-1.63 x 10(5)CFU/g in the exposed fish. The results suggest that immune suppression of the fish occurred due to heavy oil stressor, and bacteria could invade in the mucus, resulting in the increasing leukocyte number to prevent infectious disease. 相似文献
105.
In aquatic environments extracellular enzymes are bound to microbial cells or exist in a free and adsorbed state. Various
filters have been used to fractionate these enzymatic activities, but enzymes may be readily adsorbed onto some materials,
and such adsorption can induce errors in the estimation of enzymatic activity. In this study we examined three filters to
determine the most suitable filter for fractionation when estimating proteolytic enzyme activity in seawater. We found that
the polycarbonate Nuclepore membrane, widely used for size fractionation because of its pore-size accuracy, was the most favorable
for this purpose, even though it adsorbed slightly more enzymes than the low-protein-binding polyethersulfone membrane. We
also found that trypsin-and chymotrypsin-type enzymes were more easily adsorbed than aminopeptidases. 相似文献
106.
Yoko KEBUKAWA Satoru NAKASHIMA Michio ISHIKAWA Kento AIZAWA Tsutomu INOUE Keiko NAKAMURA‐MESSENGER Michael E. ZOLENSKY 《Meteoritics & planetary science》2010,45(3):394-405
Abstract– Distributions of organic functional groups as well as inorganic features were analyzed in the Bells (CM2) carbonaceous chondrite using near‐field infrared (NFIR) spectroscopy. NFIR spectroscopy has recently been developed to enable infrared spectral mapping beyond the optical diffraction limit of conventional Fourier transform infrared microspectroscopy. NFIR spectral mapping of the Bells 300 nm thick sections on Al plates for 7.5 × 7.5 μm2 areas showed some C‐H‐rich areas which were considered to represent the organic‐rich areas. Heterogeneous distributions of organic matter as well as those of inorganic phases such as silicates (Si‐O) were observed with 1 μm spatial resolution. The NFIR mappings of aliphatic C‐H (2960 and 2930 cm?1) and structural OH (3650 cm?1) confirm that organic matter is associated with phyllosilicates as previously suggested. The NFIR mapping method can provide 1 μm spatial distribution of organic functional groups and their association with minerals. High local sensitivity of NFIR enables us to find organic‐rich areas and to characterize them by their aliphatic CH2/CH3 ratios. The aliphatic CH2/CH3 ratio of Bells is slightly higher than Murchison, similar to Orgueil, and lower than literature values of IDPs and cometary dust particles. 相似文献
107.
108.
Earthquake early warning: Concepts,methods and physical grounds 总被引:2,自引:0,他引:2
Claudio Satriano Yih-Min Wu Aldo Zollo Hiroo Kanamori 《Soil Dynamics and Earthquake Engineering》2011
Modern technology allows real-time seismic monitoring facilities to evolve into earthquake early warning (EEW) systems, capable of reducing deaths, injuries, and economic losses, as well as of speeding up rescue response and damage recovery. The objective of an EEW system is to estimate in a fast and reliable way the earthquake’s damage potential, before the strong shaking hits a given target. 相似文献
109.
Analysis of summertime atmospheric transport of fine particulate matter in Northeast Asia 总被引:1,自引:0,他引:1
Hikari Shimadera Hiroshi Hayami Yu Morino Toshimasa Ohara Satoru Chatani Shuichi Hasegawa Naoki Kaneyasu 《Asia-Pacific Journal of Atmospheric Sciences》2013,49(3):347-360
In Northeast Asia, the effect of long-range transport of air pollutants is generally pronounced in spring and winter, but can be important even in summer. This study analyzed summer-time atmospheric transport of elemental carbon (EC) and sulfate (SO4 2?) with the Community Multiscale Air Quality (CMAQ) model driven by the Weather Research and Forecasting (WRF) model. The WRF/CMAQ modeling system was applied to regions ranging from Northeast Asia to the Greater Tokyo Area in Japan in summer 2007. In terms of EC, while the model simulated well the effect of long-range transport, the simulation results indicated that domestic emissions in Japan dominantly contributed (85%) to EC concentrations in the Greater Tokyo. In terms of SO4 2?, the simulation results indicated that both domestic emissions (62%) and long-range transport from the other countries (38%) substantially contributed to SO4 2? concentrations in the Greater Tokyo. Distinctive transport processes of SO4 2? were associated with typical summer-time meteorological conditions in the study region. When a Pacific high-pressure system covered the main island of Japan, domestic emissions, including volcanic emission, dominantly contributed to SO4 2? concentrations in the Greater Tokyo. When a high-pressure system prevailed over the East China Sea and low-pressure systems passed north of Japan, synoptic westerly winds associated with this pressure pattern transported a large amount of SO4 2? from the continent to Japan. In addition, although heavy precipitation and strong wind decreased SO4 2? concentrations near the center of a typhoon, peripheral typhoon winds occasionally played an important role in long-range transport of SO4 2?. 相似文献
110.